A numerical study of the influence of ammonia addition on the auto-ignition limits of methane/air mixtures.
In this study the auto-ignition limit of ammonia/methane/air mixtures is calculated based upon a perfectly stirred reactor model with convective heat transfer. The results of four different reaction mechanisms are compared with existing experimental data at an initial temperature of 723 K with ammonia concentrations of 0-20 mol.% and methane concentrations of 2.5-10 mol.%. It is found that the calculation of the auto-ignition limit pressure at constant temperature leads to larger relative deviations between calculated and experimental results than the calculation of the auto-ignition temperature at constant pressure. In addition to the calculations, a reaction path analysis is performed to explain the observed lowering of the auto-ignition limit of methane/air mixtures by ammonia addition. It is found that this decrease is caused by the formation of NO and NO(2), which enhance the oxidation of methane at low temperatures.
Van den Schoor
F
F
Department of Mechanical Engineering, Katholieke Universiteit Leuven, Leuven, Belgium. filip.vandenschoor@mech.kuleuven.be
Norman
F
F
Vandebroek
L
L
Verplaetsen
F
F
Berghmans
J
J
D000388:Air; D000641:Ammonia / Q000737:chemistry*; D053834:Explosive Agents / Q000737:chemistry*; D008697:Methane / Q000737:chemistry*; D008962:Models, Theoretical; D009569:Nitric Oxide; D009585:Nitrogen Dioxide
D053834:Explosive Agents; D009569:Nitric Oxide; D000641:Ammonia; D008697:Methane; D009585:Nitrogen Dioxide